i386/80097: df reports incorrect stats with gmirror

[Ben O'Hara]

>Number:         80097
>Category:       i386
>Synopsis:       df reports incorrect stats with gmirror
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-i386
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Tue Apr 19 11:50:21 GMT 2005
>Closed-Date:
>Last-Modified:
>Originator:     Ben O'Hara
>Release:        5.3-RELEASE
>Organization:
Trigold
>Environment:
FreeBSD doc-store01.trigold.co.uk 5.3-RELEASE FreeBSD 5.3-RELEASE #0: Fri Nov  5 04:19:18 UTC 2004     root at harlow.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  i386

>Description:
Using a gmiror mirrored disk setup 

doc-store01# gmirror list
Geom name: gm0s1
State: COMPLETE
Components: 2
Balance: round-robin
Slice: 4096
Flags: NONE
SyncID: 1
ID: 1459419299
Providers:
1. Name: mirror/gm0s1
   Mediasize: 146812989952 (137G)
   Sectorsize: 512
   Mode: r6w6e1
Consumers:
1. Name: da0s1
   Mediasize: 146812990464 (137G)
   Sectorsize: 512
   Mode: r6w6e2
   State: ACTIVE
   Priority: 0
   Flags: DIRTY
   SyncID: 1
   ID: 1511566181
2. Name: da1s1
   Mediasize: 146812990464 (137G)
   Sectorsize: 512
   Mode: r6w6e2
   State: ACTIVE
   Priority: 0
   Flags: DIRTY
   SyncID: 1
   ID: 3697187295

Geom name: gm0s1.sync


Then using df gives incorrect values for the percentage of disk space used (assuming the used/available results are correct)

doc-store01# df -k /apps
Filesystem         1K-blocks     Used     Avail Capacity  Mounted on
/dev/mirror/gm0s1g 133553752 16280212 106589240    13%    /apps

however, (106589240/133553752)*100 = ~80% free and not 13% used as reported by df.
>How-To-Repeat:
Mirror 2 disks into a gmirror, mount and use df to check used space.
>Fix:
unknown
>Release-Note:
>Audit-Trail:
>Unformatted: